N900 software power management - Revision history

imported_>joerg_rw: /* Powertop */ http://maemo.org/packages/view/zzztop/

2017-09-04T18:03:14Z

Powertop: http://maemo.org/packages/view/zzztop/

← Older revision		Revision as of 18:03, 4 September 2017
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	===Powertop===		===Powertop===

	Obsolete by zzztop		Obsolete by http://maemo.org/packages/view/zzztop/

	The output of powertop, when run as root, is shown below, with some comments. Much of the output is probably not directly useful for you.		The output of powertop, when run as root, is shown below, with some comments. Much of the output is probably not directly useful for you.

imported_>joerg_rw: /* Powertop */ d

2017-09-04T18:00:14Z

Powertop: d

← Older revision		Revision as of 18:00, 4 September 2017
Line 140:		Line 140:
	===Powertop===		===Powertop===

	~~Obsoleted~~ by zzztop		Obsolete by zzztop

	The output of powertop, when run as root, is shown below, with some comments. Much of the output is probably not directly useful for you.		The output of powertop, when run as root, is shown below, with some comments. Much of the output is probably not directly useful for you.

imported_>joerg_rw: /* Powertop */ zzztop

2017-09-04T17:59:12Z

Powertop: zzztop

← Older revision		Revision as of 17:59, 4 September 2017
Line 139:		Line 139:

	===Powertop===		===Powertop===

			Obsoleted by zzztop

	The output of powertop, when run as root, is shown below, with some comments. Much of the output is probably not directly useful for you.		The output of powertop, when run as root, is shown below, with some comments. Much of the output is probably not directly useful for you.

imported_>joerg_rw: Undo revision 46286 by 86.9.255.155 (Talk) MAN page!

2012-01-10T04:00:00Z

Undo revision 46286 by 86.9.255.155 (Talk) MAN page!

← Older revision		Revision as of 04:00, 10 January 2012
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	apt-get install strace		apt-get install strace

	strace shows what system calls the process is making. [http://linux.die.net/man/1/strace The ~~mainpage~~] has more information.		strace shows what system calls the process is making. [http://linux.die.net/man/1/strace The manpage] has more information.

	The most basic usage is:		The most basic usage is:

86.9.255.155: corrected typo

2012-01-10T03:13:42Z

corrected typo

← Older revision		Revision as of 03:13, 10 January 2012
Line 238:		Line 238:
	apt-get install strace		apt-get install strace

	strace shows what system calls the process is making. [http://linux.die.net/man/1/strace The ~~manpage~~] has more information.		strace shows what system calls the process is making. [http://linux.die.net/man/1/strace The mainpage] has more information.

	The most basic usage is:		The most basic usage is:

imported_>speedevil at 18:30, 3 August 2011

2011-08-03T18:30:50Z

← Older revision		Revision as of 18:30, 3 August 2011
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	~~This is a work in progress. It is not yet ready for public consumption. Please don't link it into wiki yet.~~

	This page may be useful to application developers, as well as those interested in reducing power usage of software by configuring it correctly.		This page may be useful to application developers, as well as those interested in reducing power usage of software by configuring it correctly.

imported_>joerg_rw: /* Powerscript */

2011-07-14T01:43:09Z

Powerscript

imported_>joerg_rw: /* Htop */ Fn keys

2011-05-01T21:58:10Z

Htop: Fn keys

← Older revision		Revision as of 21:58, 1 May 2011
Line 258:		Line 258:
	apt-get install htop		apt-get install htop

	Full documentation can be found [http://htop.sourceforge.net/ at the htop project pages on sourceforge]		Full documentation can be found [http://htop.sourceforge.net/ at the htop project pages on sourceforge] (in case you wonder: the F(n)-keys can get typed on N900 as ESC-<n>, so ESC + "1" for F1)

	[[image:htop.png]]		[[image:htop.png]]

62.108.25.47: /* What is power? */ active but idle

2011-03-06T05:44:19Z

What is power?: active but idle

← Older revision		Revision as of 05:44, 6 March 2011
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	The below tools directly measure electrical current usage by the phone. They should be run with the device unplugged from USB. Battery capacity is measured in Amp-Hours. The BL-5J in the N900 has a capacity of 1.4 Ah. It can provide 1 A for a little over an hour, but it's very hard to get it to use that much. If the current drops, the time rises.		The below tools directly measure electrical current usage by the phone. They should be run with the device unplugged from USB. Battery capacity is measured in Amp-Hours. The BL-5J in the N900 has a capacity of 1.4 Ah. It can provide 1 A for a little over an hour, but it's very hard to get it to use that much. If the current drops, the time rises.

	For example, in standby with wifi and phone ~~active~~ but idle, the current usage is around .006 A, leading to a standby life of around 10 days. (1.4 Ah/.006 A = 220 h = 10 days. 0.006 A is a cumbersome figure, so the unit 'Milliamp' - mA - 1/1000th of an amp is used. 6 mA when idle is great, but it is easy if everything does not go right to use lots more than this when idle. For example, if the CPU is constantly active, it will use over 100 mA - draining the battery in around 12 hours.		For example, in standby with wifi and phone enabled but idle, the current usage is around .006 A, leading to a standby life of around 10 days. (1.4 Ah/.006 A = 220 h = 10 days. 0.006 A is a cumbersome figure, so the unit 'Milliamp' - mA - 1/1000th of an amp is used. 6 mA when idle is great, but it is easy if everything does not go right to use lots more than this when idle. For example, if the CPU is constantly active, it will use over 100 mA - draining the battery in around 12 hours.

	==Debugging==		==Debugging==

imported_>joerg_rw at 16:55, 14 November 2010

2010-11-14T16:55:51Z

← Older revision		Revision as of 16:55, 14 November 2010
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	This page may be useful to application developers, as well as those interested in reducing power usage of software by configuring it correctly.		This page may be useful to application developers, as well as those interested in reducing power usage of software by configuring it correctly.

			Also refer to http://www.lesswatts.org/projects/applications-power-management/

	==Why software uses power==		==Why software uses power==

← Older revision		Revision as of 01:43, 14 July 2011
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	if [[ -e /sys/class/power_supply/bq27200-0/current_now ]]		if [[ -e /sys/class/power_supply/bq27200-0/current_now ]]
	then		then
	current_read='cat /sys/class/power_supply/bq27200-0/current_now'		current_read='cat /sys/class/power_supply/bq27200-0/current_now'
	echo Using kernel battery driver to read current.		echo Using kernel battery driver to read current.
	else		else
	if command -v i2cget >/dev/null		if command -v i2cget >/dev/null
	then		then
	current_read='i2cget -y 2 0x55 0x14 w'		current_read='i2cget -y 2 0x55 0x14 w'
	echo Using I2C to read charge meter directly		echo "Using I2C to read charge meter directly"
	else		else
	echo Cannot find a way to read the charge meter.		echo "Cannot find a way to read the charge meter."
	echo Either i2ctools from extras-devel must be installed, or the power kernel with the bq27x00_battery module which normally accompanies it.		echo "Either i2ctools from extras-devel must be installed, or the power kernel with the bq27x00_battery module which normally accompanies it."
	echo Exiting.		echo "Exiting."
	exit		exit
	fi		fi
	fi		fi
	# Reset timer stats.		# Reset timer stats.
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	while true # Loop while printing stats		while true # Loop while printing stats
	do		do
	echo 1 >/proc/timer_stats # Start gathering stats		echo 1 >/proc/timer_stats # Start gathering stats
	sleep 5 # Sleep 5s		sleep 5 # Sleep 5s
	echo 0 >/proc/timer_stats # Finish stats.		echo 0 >/proc/timer_stats # Finish stats.
	# Print output, assuming sense resistor is 22 milliohms.		# Print output, assuming sense resistor is 22 milliohms.
	echo `date` $((`$current_read` * 3570 / 22 / 1000))mA `tail -1 /proc/timer_stats`		echo `date` $((`$current_read` * 3570 / 22 / 1000))mA `tail -1 /proc/timer_stats`
	done		done
	</source>		</source>
Line 125:		Line 125:
	...		...

	This shows that immediately after starting, the script measured over the first 5 s a power consumption of 25 mA. This will discharge in one hour the battery by 25 milliamp-hours. It has a total capacity of around 1200 mAh - so will last about 1200 mAh/25 mA = 75 hours (roughly).		This shows that immediately after starting, the script measured over the first 5 s (actually for the 5s window that ended before script started) a power consumption of 25 mA. This will discharge in one hour the battery by 25 milliamp-hours. It has a total capacity of around 1200 mAh - so will last about 1200 mAh/25 mA = 75 hours (roughly).

	Wifi however uses a significant amount of power. By comparison, this is the result when redirecting the output to a file.		Wifi however uses a significant amount of power. By comparison, this is the result when redirecting the output to a file.